What is unique about pluto's orbit around the sun?
revolves opposite to all other planets
inclined more than other planets
most circular orbit
most elliptical orbit

most elliptical orbit

Explanation:                    

Pluto is a dwarf planet which lies beyond Neptune. It is the first object in the Kuiper belt which was found by Clyde Tombaugh in 1930. Pluto's orbit is 17° tilted and it does not lie in the same plane as other planets revolve around Sun. It takes 248 years for Pluto to complete one orbit. Its orbit is most elliptical in nature.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.